Power management for microbial fuel cells

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Monitoring parameters characterizing water quality, such as temperature, pH and concentrations of heavy metals in natural waters, is often followed by transmitting the data to remote receivers using telemetry systems. Such systems are commonly powered by batteries, which can be inconvenient at times because batteries have a limited lifetime and have to be recharged or replaced periodically to ensure that sufficient energy is available to power the electronics. To avoid these inconveniences, we have designed and tested a self-renewable power source, a microbial fuel cell, which has the potential to eliminate the need for batteries to power electrochemical sensors used to monitor water quality and small telemetry systems used to transmit the data acquired by these sensors. To demonstrate the utility of the microbial fuel cell, we have combined it with low-power, high-efficiency electronic circuitry providing a stable power source for wireless data transmission. To generate enough power for the telemetry system, energy produced by the microbial fuel cell was stored in an ultracapacitor and used in short bursts when needed. Since powering commercial components of electronic circuits requires 5 Volts, and our cell was able to deliver a maximum of 2.1 V, we used a DC-DC converter to increase the potential. The DC-DC converter powered the transmitter, which gathered the data from the sensor and transmitted them to a receiver. To demonstrate the utility of the system, we initially measured temporal variations in temperature followed by the implementation of a chemical sensor to measure copper and lead concentrations in water; this data was then wirelessly transmitted to a remote receiver.